ADP3419JRMZ-REEL1 [ADI]
Dual Bootstrapped, High Voltage MOSFET Driver with Output Disable; 双自举，高电压MOSFET驱动器输出禁用
| 型号： | ADP3419JRMZ-REEL1 |
| 厂家： | 
ADI |
| 描述： | Dual Bootstrapped, High Voltage MOSFET Driver with Output Disable |
| 文件： | 总16页 (文件大小：393K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Dual Bootstrapped, High Voltage MOSFET
Driver with Output Disable
ADP3419
FEATURES
SIMPLIFIED FUNCTIONAL BLOCK DIAGRAM
All-in-one synchronous buck driver
One PWM signal generates both drives
Anticross-conduction protection circuitry
Output disable function
Crowbar control
Synchronous override control
Undervoltage lockout
VCC
5
BST
10
1
2
9
8
DRVH
SW
IN
UVLO,
OVERLAP
PROTECTION,
SHUTDOWN
AND
SD
3
4
DRVLSD
CROWBAR
CIRCUITS
APPLICATIONS
6
DRVL
CROWBAR
Mobile computing CPU core power converters
Multiphase desk-note CPU supplies
ADP3419
7
Single-supply synchronous buck converters
Nonsynchronous-to-synchronous drive conversion
GND
Figure 1.
GENERAL DESCRIPTION
The ADP3419 is a dual MOSFET driver optimized for driving
two N-channel switching MOSFETs in nonisolated synchro-
nous buck power converters used to power CPUs in portable
computers. The driver impedances have been chosen to provide
optimum performance in multiphase regulators at up to 25 A
per phase. The high-side driver can be bootstrapped relative to
the switch node of the buck converter and is designed to
accommodate the high voltage slew rate associated with floating
high-side gate drivers.
GENERAL APPLICATION CIRCUIT
5V
VDC
5
VCC
FROM CONTROLLER
1
2
3
IN
10
9
BST
PWM OUTPUT
ADP3419
FROM SYSTEM
ENABLE CONTROL
DRVH
SW
V
SD
OUT
FROM
CONTROLLER
8
6
DRVLSD
The ADP3419 includes an anticross-conduction protection
circuit, undervoltage lockout to hold the switches off until the
driver has sufficient voltage for proper operation, a crowbar
input that turns on the low-side MOSFET independently of the
input signal state, and a low-side MOSFET disable pin to
FROM CONTROLLER
CLAMP OUTPUT
4
CROWBAR DRVL
GND
7
Figure 2.
SD
provide higher efficiency at light loads. The
pin shuts off
both the high-side and the low-side MOSFETs to prevent rapid
output capacitor discharge during system shutdown.
The ADP3419 is specified over the extended commercial
temperature range of 0°C to 100°C and is available in a 10-lead
MSOP package.
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
www.analog.com
© 2005 Analog Devices, Inc. All rights reserved.
ADP3419
TABLE OF CONTENTS
Specifications..................................................................................... 3
Low-Side Driver Shutdown....................................................... 10
Low-Side Driver Timeout ......................................................... 10
Crowbar Function...................................................................... 10
Application Information................................................................ 11
Supply Capacitor Selection ....................................................... 11
Bootstrap Circuit........................................................................ 11
Power and Thermal Considerations........................................ 11
PC Board Layout Considerations............................................. 12
Outline Dimensions....................................................................... 13
Ordering Guide .......................................................................... 13
Absolute Maximum Ratings............................................................ 5
ESD Caution.................................................................................. 5
Pin Configuration and Function Descriptions............................. 6
Typical Performance Characteristics ............................................. 7
Theory of Operation ........................................................................ 9
Undervoltage Lockout ................................................................. 9
Driver Control Input.................................................................... 9
Low-Side Driver............................................................................ 9
High-Side Driver .......................................................................... 9
Overlap Protection Circuit.......................................................... 9
REVISION HISTORY
3/05—Rev. 0 to Rev. A
Updated Format..................................................................Universal
Changes to Specifications................................................................ 3
4/04—Revision 0: Initial Version
Rev. A | Page 2 of 16
ADP3419
SPECIFICATIONS
SD
VCC =
= 5 V, BST = 4 V to 26 V, TA = 0°C to 100°C, unless otherwise noted.
All limits at temperature extremes are guaranteed via correlation using standard statistical quality control (SQC) methods.
Table 1.
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
LOGIC INPUTS (IN, SD, DRVLSD, CROWBAR)
Input Voltage High
Input Voltage Low
Input Current
DRVLSD Propagation Delay Time
VIH
VIL
IIN
2.0
−1
V
V
µA
ns
0.8
+1
Inputs = 0 V or 5 V
CLOAD = 3 nF, Figure 3
tpdl
,
20
DRVLSD
tpdh
DRVLSD
HIGH-SIDE DRIVER
Output Resistance, Sourcing Current
Output Resistance, Sinking Current
Transition Times
BST − SW = 4.6 V
BST − SW = 4.6 V
BST − SW = 4.6 V, CLOAD = 3 nF, Figure 4
BST − SW = 4.6 V, CLOAD = 3 nF, Figure 4
BST − SW = 4.6 V, CLOAD = 3 nF, Figure 4
BST − SW = 4.6 V, CLOAD = 3 nF, Figure 4
1.7
0.8
14
11
32
28
3.3
2.3
35
25
70
60
Ω
Ω
ns
ns
ns
ns
trDRVH
tfDRVH
tpdhDRVH
tpdlDRVH
Propagation Delay Times1
15
LOW-SIDE DRIVER
Output Resistance, Sourcing Current
Output Resistance, Sinking Current
Transition Times
1.7
0.8
13
11
25
16
350
1
3.3
2.3
30
25
48
Ω
Ω
trDRVL
tfDRVL
tpdhDRVL
tpdlDRVL
tSWTO
VZC
CLOAD = 3 nF, Figure 4
CLOAD = 3 nF, Figure 4
CLOAD = 3 nF, Figure 4
CLOAD = 3 nF, Figure 4
BST − SW = 4.6 V
ns
ns
ns
ns
ns
V
Propagation Delay Times1, 2
30
600
SW Transition Timeout2
Zero-Crossing Threshold
SUPPLY
Supply Voltage Range
Supply Current
150
4.6
VCC
6
V
Normal Mode
Shutdown Mode
ISYS(NM)
ISYS(SD)
ICC + IBST, IN = 0 V or 5 V
ICC + IBST, SD = 0 V
VCC rising
0.8
1.5
600
4.5
mA
µA
V
325
4.25
120
Undervoltage Lockout Threshold
Undervoltage Lockout Hysteresis3
3.8
50
VCC falling
mV
1 For propagation delays, tpdh refers to the specified signal going high, and tpdl refers to the signal going low with transitions measured at 50%.
2 The turn-on of DRVL is initiated after IN goes low by either SW crossing a ~1 V threshold or by expiration of tSWTO
3 Guaranteed by characterization, not production tested.
.
Rev. A | Page 3 of 16
ADP3419
IN
2.0V
DRVLSD
0.8V
tpdhDRVLSD
tpdlDRVLSD
DRVL
Figure 3. Output Disable Timing Diagram (Timing is Referenced to the 90% and 10% Points Unless Otherwise Noted)
IN
t
t DRVL
f
pdlDRVL
t
rDRVL
t
pdlDRVH
DRVL
t
f
DRVH
t
t
pdhDRVH
r
DRVH
DRVH-SW
V
V
TH
TH
SW
t
pdhDRVL
1V
≤
tSWTO
Figure 4. Nonoverlap Timing Diagram (Timing is Referenced to the 90% and 10% Points Unless Otherwise Noted)
Rev. A | Page 4 of 16
ADP3419
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those listed in the operational sections
of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Rating
VCC
BST
BST to SW
SW
DRVH
DRVL
−0.3 V to +7 V
−0.3 V to +30 V
−0.3 V to +7 V
−3 V to +25 V
SW − 0.3 V to BST + 0.3 V
−0.3 V to VCC + 0.3 V
−0.3 V to VCC + 0.3 V
Unless otherwise specified, all voltages are referenced to GND.
All Other Inputs and Outputs
θJA
2-Layer Board
4-Layer Board
340°C/W
220°C/W
Operating Ambient Temperature
Range
0°C to 100°C
Junction Temperature Range
Storage Temperature Range
Lead Temperature Range
Soldering (10 s)
Vapor Phase (60 s)
Infrared (15 s)
0°C to 150°C
−65°C to +150°C
300°C
215°C
220°C
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the
human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
Rev. A | Page 5 of 16
ADP3419
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
1
2
3
4
5
10
9
IN
SD
BST
DRVH
SW
ADP3419
TOP VIEW
8
DRVLSD
CROWBAR
VCC
(Not to Scale)
7
GND
DRVL
6
Figure 5. Pin Configuration
Table 3. Pin Function Descriptions
Pin No. Mnemonic Function
1
IN
Logic Level PWM Input. This pin has primary control of the drive outputs. In normal operation, pulling this pin
low turns on the low-side driver; pulling it high turns on the high-side driver.
2
3
SD
Shutdown Input. When low, this pin disables normal operation, forcing DRVH and DRVL low.
Synchronous Rectifier Shutdown Input. When low, DRVL is forced low; when high, DRVL is enabled and
controlled by IN and by the adaptive overlap protection control circuitry.
DRVLSD
4
5
6
7
8
CROWBAR
VCC
DRVL
GND
Crowbar Input. When high, DRVL is forced high regardless of the high-side MOSFET switch condition.
Input Supply. This pin should be bypassed to GND with a 4.7 µF or larger ceramic capacitor.
Synchronous Rectifier Drive. Output drive for the lower (synchronous rectifier) MOSFET.
Ground. This pin should be closely connected to the source of the lower MOSFET.
Switch Node Input. This pin is connected to the buck-switching node, close to the upper MOSFET’s source. It is
the floating return for the upper MOSFET drive signal. It is also used to monitor the switched voltage to prevent
turn-on of the lower MOSFET until the voltage is below ~1 V.
SW
9
10
DRVH
BST
Buck Drive. Output drive for the upper (buck) MOSFET.
Upper MOSFET Floating Bootstrap Supply. A capacitor connected between the BST and SW pins holds this
bootstrapped voltage for the high-side MOSFET as it is switched.
Rev. A | Page 6 of 16
ADP3419
TYPICAL PERFORMANCE CHARACTERISTICS
25
20
15
10
5
VCC = 5V
= 3nF
C
LOAD
RISE TIME
FALLTIME
0
0
25
50
75
100
125
JUNCTION TEMPERATURE (°C)
Figure 6. DRVH Rise and DRVL Fall Times
CH1 = IN, CH2 = DRVH, CH3 = DRVL
Figure 9. DRVL Rise and Fall Times vs. Temperature
80
60
40
20
0
VCC = 5V
T
= 25°C
A
DRVH
DRVL
0
2
4
6
8
10
LOAD CAPACITANCE (nF)
Figure 7. DRVH Fall and DRVL Rise Times
CH1 = IN, CH2 = DRVH, CH3 = DRVL
Figure 10. DRVH and DRVL Rise Times vs. Load Capacitance
25
25
VCC = 5V
= 25°C
VCC = 5V
DRVH
DRVL
T
A
C
= 3nF
LOAD
20
15
10
5
20
15
10
5
RISE TIME
FALLTIME
0
0
0
25
50
75
100
125
0
2
4
6
8
10
JUNCTION TEMPERATURE (°C)
LOAD CAPACITANCE (nF)
Figure 8. DRVH Rise and Fall Times vs. Temperature
Figure 11. DRVH and DRVL Fall Times vs. Load Capacitance
Rev. A | Page 7 of 16
ADP3419
50
50
40
30
20
10
0
VCC = BST = 5V
= 3nF
VCC = 5V
= 3nF
tpdhDRVH
C
LOAD
C
LOAD
T
= 25°C
A
40
30
20
10
0
tpdhDRVL
0
25
50
75
100
125
0
200
400
600
800
1000
1200
JUNCTION TEMPERATURE (°C)
IN FREQUENCY (kHz)
Figure 12. DRVH and DRVL tpdh vs. Temperature
Figure 15. Supply Current vs. Frequency
40
30
20
10
0
1.5
1.0
0.5
0
VCC = 5V
= 3nF
VCC = 5V
tpdlDRVH
C
LOAD
C
= 3nF
LOAD
tpdlDRVL
0
25
50
75
100
125
0
25
50
75
100
125
JUNCTION TEMPERATURE (°C)
JUNCTION TEMPERATURE (°C)
Figure 13. DRVH and DRVL tpdl vs. Temperature
Figure 16. Supply Current vs. Temperature
100
80
60
40
20
0
VCC = 5V
C
= 3nF
LOAD
T
= 25°C
A
0
1
2
3
4
5
INPUT VOLTAGE (V)
Figure 14. IN Pin Input Current vs. Input Voltage
Rev. A | Page 8 of 16
ADP3419
THEORY OF OPERATION
The ADP3419 is a dual MOSFET driver optimized for driving
two N-channel MOSFETs in a synchronous buck converter
topology. A single PWM input signal is all that is required to
properly drive the high-side and the low-side MOSFETs. Each
driver is capable of driving a 3 nF load at speeds up to 1 MHz. A
more detailed description of the ADP3419 and its features
follows. Refer to the detailed block diagram in Figure 17.
HIGH-SIDE DRIVER
The high-side driver is designed to drive a floating low RDS(ON)
N-channel MOSFET. The bias voltage for the high-side driver is
developed by an external bootstrap supply circuit, which is
connected between the BST and SW pins.
The bootstrap circuit comprises a diode, D1, and bootstrap
capacitor, CBST. When the ADP3419 is starting up, the SW pin is
at ground, so the bootstrap capacitor charges up to VCC
through D1. Once the supply voltage ramps up and exceeds the
UVLO threshold, the driver is enabled. When IN goes high, the
high-side driver begins to turn on the high-side MOSFET (Q1)
by transferring charge from CBST. As Q1 turns on, the SW pin
rises up to VDCIN, forcing the BST pin to VDCIN + VC(BST), which is
enough gate-to-source voltage to hold Q1 on. To complete the
cycle, Q1 is switched off by pulling the gate down to the voltage
at the SW pin. When the low-side MOSFET (Q2) turns on, the
SW pin is pulled to ground. This allows the bootstrap capacitor
to charge up to VCC again.
5V
V
DCIN
D1
VCC
5
ADP3419
UVLO
AND BIAS
4
1
CROWBAR
IN
BST
10
9
R
BST
C
BST
+
DRVH
SW
Q1
OVERLAP
PROTECTION
AND
2
SD
8
6
TIME-OUT
CIRCUIT
When the driver is enabled, the driver’s output is in phase with
the IN pin. Table 4 shows the relationship between DRVH and
the different control inputs of the ADP3419.
VCC
DRVL
Q2
3
DRVLSD
7
OVERLAP PROTECTION CIRCUIT
GND
The overlap protection circuit prevents both main power
switches, Q1 and Q2, from being on at the same time. This is
done to prevent shoot-through currents from flowing through
both power switches and the associated losses that can occur
during their on-off transitions. The overlap protection circuit
accomplishes this by adaptively controlling the delay from Q1’s
turn-off to Q2’s turn-on, and the delay from Q2’s turn-off to
Q1’s turn-on.
Figure 17. Detailed Block Diagram of the ADP3419
UNDERVOLTAGE LOCKOUT
The undervoltage lockout (UVLO) circuit holds both MOSFET
driver outputs low during VCC supply ramp-up. The UVLO
logic becomes active and in control of the driver outputs at a
supply voltage of no greater than 1.5 V. The UVLO circuit waits
until the VCC supply has reached a voltage high enough to bias
logic level MOSFETs fully on before releasing control of the
drivers to the control pins.
To prevent the overlap of the gate drives during Q1’s turn-off
and Q2’s turn-on, the overlap circuit monitors the voltage at the
SW pin and DRVH pin. When IN goes low, Q1 begins to turn
off. The overlap protection circuit waits for the voltage at the
SW and DRVH pins to both fall below 1.6 V. Once both of these
conditions are met, Q2 begins to turn on. Using this method,
the overlap protection circuit ensures that Q1 is off before Q2
turns on, regardless of variations in temperature, supply voltage,
gate charge, and drive current. There is, however, a timeout
circuit that overrides the waiting period for the SW and DRVH
pins to reach 1.6 V. After the timeout period has expired, DRVL
is asserted high regardless of the SW and DRVH voltages. In the
opposite case, when IN goes high, Q2 begins to turn off after a
propagation delay. The overlap protection circuit waits for the
voltage at DRVL to fall below 1.6 V, after which DRVH is
asserted high and Q1 turns on.
DRIVER CONTROL INPUT
The driver control input (IN) is connected to the duty ratio
modulation signal of a switch-mode controller. IN can be
driven by 2.5 V to 5.0 V logic. The output MOSFETs are driven
so that the SW node follows the polarity of IN.
LOW-SIDE DRIVER
The low-side driver is designed to drive a ground-referenced
low RDS(ON) N-channel synchronous rectifier MOSFET. The bias
to the low-side driver is internally connected to the VCC supply
and GND. Once the supply voltage ramps up and exceeds the
UVLO threshold, the driver is enabled. When the driver is
enabled, the driver’s output is 180° out of phase with the IN pin.
Table 4 shows the relationship between DRVL and the different
control inputs of the ADP3419.
Rev. A | Page 9 of 16
ADP3419
LOW-SIDE DRIVER SHUTDOWN
CROWBAR FUNCTION
DRVLSD
In addition to the internal low-side drive time-out circuit, the
ADP3419 includes a CROWBAR input pin to provide a means
for additional overvoltage protection. When CROWBAR goes
high, the ADP3419 turns off DRVH and turns on DRVL. The
crowbar logic overrides the overlap protection circuit, the
The low-side driver shutdown
to shut down the synchronous rectifier. Under light load
DRVLSD
allows a control signal
conditions,
reversal of the inductor current to maximize light load
DRVLSD
should be pulled low before the polarity
conversion efficiency.
can also be pulled low for
DRVLSD
shutdown logic, the
logic, and the UVLO protection
reverse voltage protection purposes.
on DRVL. Thus, the crowbar function maximizes the overvolt-
age protection coverage in the application. The CROWBAR can
be either driven by the CLAMP pin of buck controllers, such as
the ADP3422, ADP3203, ADP3204, or ADP3205, or controlled
by an independent overvoltage monitoring circuit.
DRVLSD
When
DRVLSD
is low, the low-side driver stays low. When
is high, the low-side driver is enabled and controlled
by the driver signals, as previously described.
LOW-SIDE DRIVER TIMEOUT
Table 4. ADP3419 Truth Table
In normal operation, the DRVH signal tracks the IN signal and
turns off the Q1 high-side switch with a few 10 ns delay
(tpdlDRVH) following the falling edge of the input signal. When Q1
is turned off, DRVL is allowed to go high, Q2 turns on, and the
SW node voltage collapses to zero. But in a fault condition such
as a high-side Q1 switch drain-source short circuit, the SW
node cannot fall to zero, even when DRVH goes low. The
ADP3419 has a timer circuit to address this scenario. Every
time the IN goes low, a DRVL on-time delay timer is triggered.
If the SW node voltage does not trigger a low-side turn-on, the
DRVL on-time delay circuit does it instead, when it times out
with tSW(TO) delay. If Q1 is still turned on, that is, its drain is
shorted to the source, Q2 turns on and creates a direct short
circuit across the VDCIN voltage rail. The crowbar action causes
the fuse in the VDCIN current path to open. The opening of the
fuse saves the load (CPU) from potential damage that the high-
side switch short circuit could have caused.
CROWBAR
UVLO SD DRVLSD
IN DRVH DRVL
L
L
L
L
L
L
H
H
L
L
L
L
L
H
L
H
H
H
H
H
L
*
*
*
H
H
L
L
*
*
*
*
H
L
H
L
*
H
L
H
L
L
L
L
L
L
H
L
L
L
*
L
*
*
H
H
* = Don’t Care.
Rev. A | Page 10 of 16
ADP3419
APPLICATION INFORMATION
SUPPLY CAPACITOR SELECTION
POWER AND THERMAL CONSIDERATIONS
For the supply input (VCC) of the ADP3419, a local bypass
capacitor is recommended to reduce the noise and to supply
some of the peak currents drawn. Use a 10 µF or 4.7 µF
multilayer ceramic (MLC) capacitor. MLC capacitors provide
the best combination of low ESR and small size, and can be
obtained from the following vendors.
The major power consumption of the ADP3419-based driver
circuit is from the dissipation of MOSFET gate charge. It can be
estimated as
PMAX ≈VCC×(QHSGATE +QLSGATE )× fMAX
(3)
where:
VCC is the supply voltage 5 V.
MAX is the highest switching frequency.
HSGATE and QLSGATE are the total gate charge of high-side and
Table 5.
Vendor
Part Number
Web Address
f
Q
Murata
GRM235Y5V106Z16 www.murata.com
Taiyo-Yuden
Tokin
EMK325F106ZF
C23Y5V1C106ZP
www.t-yuden.com
www.tokin.com
low-side MOSFETs, respectively.
For example, the ADP3419 drives two IRF7821 high-side
MOSFETs and two IRF7832 low-side MOSFETs. According to
Keep the ceramic capacitor as close as possible to the ADP3419.
the MOSFET data sheets, QHSGATE = 18.6 nC and QLSGATE
68 nC. Given that fMAX is 300 kHz, PMAX would be about
130 mW.
=
BOOTSTRAP CIRCUIT
The bootstrap circuit uses a charge storage capacitor (CBST) and
a Schottky diode (D1), as shown in Figure 17. Selection of these
components can be done after the high-side MOSFET has been
chosen. The bootstrap capacitor must have a voltage rating that
is able to handle at least 5 V more than the maximum supply
voltage. The capacitance is determined by
Part of this power consumption generates heat inside the
ADP3419. The temperature rise of the ADP3419 against its
environment is estimated as
∆T ≈ θJA ×PMAX ×η
(4)
QHSGATE
∆VBST
CBST
=
(1)
where θJA is ADP3419’s thermal resistance from junction to air,
given in the absolute maximum ratings as 220°C/W for a
4-layer board.
where:
HSGATE is the total gate charge of the high-side MOSFET.
∆VBST is the voltage droop allowed on the high-side MOSFET
Q
The total MOSFET drive power dissipates in the output
resistance of ADP3419 and in the MOSFET gate resistance as
well. η represents the ratio of power dissipation inside the
ADP3419 over the total MOSFET gate driving power. For
normal applications, a rough estimation for η is 0.7. A more
accurate estimation can be calculated using
drive.
For example, two IRF7811 MOSFETs in parallel have a total
gate charge of about 36 nC. For an allowed droop of 100 mV,
the required bootstrap capacitance is 360 nF. A good quality
ceramic capacitor should be used, and derating for the signifi-
cant capacitance drop of MLCs at high temperature must be
applied. In this example, selection of 470 nF or even 1 µF would
be recommended.
QHSGATE
QHSGATE + QLSGATE
0.5× R1
0.5× R2
⎛
⎜
⎞
⎟
η ≈
×
+
R1+ RHSGATE + R R2 + RHSGATE
⎝
⎠
(5)
QLSGATE
QHSGATE + QLSGATE
0.5× R3
R3 + RLSGATE R4 + RLSGATE
0.5× R4
⎛
⎜
⎞
⎟
+
×
+
⎝
⎠
A Schottky diode is recommended for the bootstrap diode due
to its low forward drop, which maximizes the drive available for
the high-side MOSFET. The bootstrap diode must also be able
to handle at least 5 V more than the maximum battery voltage.
The average forward current can be estimated by
where:
R1 and R2 are the output resistances of the high-side driver:
R1 = 1.7 (DRVH − BST), R2 = 0.8 (DRVH − SW).
R3 and R4 are the output resistances of the low-side driver:
R3 = 1.7 (DRVL − VCC), R4 = 0.8 (DRVL − GND).
R is the external resistor between the BST pin and the BST
capacitor.
IF(AVG) = QHSGATE × fMAX
(2)
where fMAX is the maximum switching frequency of the
R
HSGATE and RLSGATE are gate resistances of high-side and low-side
controller.
MOSFETs, respectively.
Assuming that R = 0 and that RHSGATE = RLSGATE = 0.5, Equation 5
gives a value of η = 0.71. Based on Equation 4, the estimated
temperature rise in this example is about 22°C.
Rev. A | Page 11 of 16
ADP3419
PC BOARD LAYOUT CONSIDERATIONS
•
Fast switching of the high-side MOSFET can reduce
switching loss. However, EMI problems can arise due to
the severe ringing of the switch node voltage. Depending
on the character of the low-side MOSFET, a very fast
turn-on of the high-side MOSFET may falsely turn on
the low-side MOSFET through the dv/dt coupling of its
Miller capacitance. Therefore, when fast turn-on of the
high-side MOSFET is not required by the application, a
resistor of about 1 Ω to 2 Ω can be placed between the
BST pin and the BST capacitor to limit the turn-on
speed of the high-side MOSFET.
Use the following general guidelines when designing printed
circuit boards. Figure 18 gives an example of the typical land
patterns based on the guidelines given here.
•
The VCC bypass capacitor should be located as close as
possible to the VCC and GND pins. Place the ADP3419
and bypass capacitor on the same layer of the board, so
that the PCB trace between the ADP3419 VCC pin and
the MLC capacitor does not contain any via. An ideal
location for the bypass MLC capacitor is near Pin 5 and
Pin 6 of the ADP3419.
D1
•
•
High frequency switching noise can be coupled into the
VCC pin of the ADP3419 via the BST diode. Therefore,
do not connect the anode of the BST diode to the VCC
pin with a short trace. Use a separate via or trace to
connect the anode of the BST diode directly to the VCC
5 V power rail.
C
R
BST
BST
TO SWITCH
NODE
It is best to have the low-side MOSFET gate close to the
DRVL pin; otherwise, use a short and very thick PCB
trace between the DRVL pin and the low-side MOSFET
gate.
SHORT, THICK TRACE
TO THE GATES OF
LOW-SIDE MOSFETS
C
VCC
Figure 18. External Component Placement Example
Rev. A | Page 12 of 16
ADP3419
OUTLINE DIMENSIONS
3.00 BSC
6
10
4.90 BSC
3.00 BSC
PIN 1
1
5
0.50 BSC
0.95
0.85
0.75
1.10 MAX
0.80
0.60
0.40
8°
0°
0.15
0.00
0.27
0.17
SEATING
PLANE
0.23
0.08
COPLANARITY
0.10
COMPLIANT TO JEDEC STANDARDS MO-187-BA
Figure 19. 10-Lead Mini Small Outline Package [MSOP]
(RM-10)
Dimensions shown in millimeters
ORDERING GUIDE
Quantity
Model
Temperature Range Package Description
Package Option per Reel
Branding
P9A
P9B
ADP3419JRM-REEL
ADP3419JRMZ-REEL1 0°C to 100°C
0°C to 100°C
10-Lead Mini Small Outline Package (MSOP)
10-Lead Mini Small Outline Package (MSOP)
RM-10
RM-10
3000
3000
1 Z = Pb-free part.
Rev. A | Page 13 of 16
ADP3419
NOTES
Rev. A | Page 14 of 16
ADP3419
NOTES
Rev. A | Page 15 of 16
ADP3419
NOTES
©2005 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D04620–0–3/05(A)
Rev. A | Page 16 of 16
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